1. Field of the Invention
This invention relates generally to epitaxial deposition of materials on a substrate and, more particularly, to epitaxial deposition of materials on a substrate in an axially symmetric configuration. Because of the axially symmetric configuration, the deposition chamber must be specifically designed to provide for uniform heating of substrate.
2. Description of the Related Art
It is known that the quality of the deposited material in an epitaxial deposition chamber can depend, among other things, on the uniformity of the temperature of the substrate and the uniformity of deposition material in the carrier gas. Recently, the advantages of epitaxial deposition in an axially symmetric configuration have been identified. The full advantage of this configuration is a commercial environment can be realized only with rapid, uniform heating of the substrate. In the prior art, massive susceptors have been heated by arrays of linear lamps or by RF fields, with temperature uniformity provided in part by the large thermal mass and high thermal conductivity of a susceptor associated with the substrate. However, the high thermal mass of the susceptor provides a thermal inertia that prolongs the heating and cooling cycles associated with the epitaxial deposition process.
A need has therefore been felt for apparatus and for a method that can rapidly and uniformly heat a wafer and, more particularly, can uniformly heat a susceptor and/or wafer of low thermal mass in an axially symmetric environment.